Evaluating the efficacy of reintroducing fishers (Pekania pennanti) to a landscape managed for timber production

Abstract

Understanding the role of landscapes managed for timber production in the conservation of forest-obligate species is a priority for preserving ecological integrity and fostering socioeconomic wellbeing. The forest characteristics generally associated with the survival, reproduction, and persistence of forest-obligate species (e.g., large-diameter trees, standing dead trees, understory vegetation, downed logs) are often believed to be at odds with timber production. One such species is the fisher (Pekania pennanti), a mesocarnivoran (member of the order Carnivora) associated with mature forest characteristics whose range has decreased substantially since the mid-1800s. Fishers exemplify the perceived conflict between forest-obligate species and timber production because they generally require areas exhibiting complex forest structure including multiple canopy layers, old trees and standing dead trees with cavities, logs, and understory vegetation that provide sufficient prey, escape cover, and structures to support reproduction and parturition. Consequently, understanding if fishers can persist in landscapes managed for timber production can provide a critical test of the compatibility among forest-obligate species and forest management. We reintroduced 40 fishers (24 females, 16 males) between November 2009 and December 2011 onto a landscape managed for timber production to establish a new fisher population and to evaluate the viability of fisher populations on a forest managed for timber production. We studied this reintroduced population of fishers for 8 years following the reintroduction using annual live-captures and year-round tracking with radio telemetry. Using population modeling with spatial capture-recapture methods, we estimated this population of fishers to be growing during the 7-year study period. The density of the reintroduced fisher population in 2017 (10.8 fishers/100 km2) was within the reported range of fisher densities across the western United States. The reintroduction of fishers to previously occupied portions of their range is an important component of fisher conservation and will play a role in the recovery of the species in western portions of the fisher's range. Our results suggest that forests managed for timber production with landscape conditions similar to our study area may be important for future fisher reintroductions and species recovery.